Reaction of Detergents with Amoeba proteus

Abstract

Amoeba proteus moves by the formation of pseudopodia in the direction of travel, and the formation of new pseudopodia may be induced by small local concentrations of some proteins and cationic detergents which are believed to react with anionic groups on the cell surface and lower the surface charge^1,2. The importance of changes in net surface charge in providing a mechanism for cell surface transformations has also been emphasized by other workers³. Staining reactions with alcian blue and with toluidine blue show that the surface coat of amoebae is probably composed of negatively charged polysaccharides or mucopolysaccharides⁴. The haemolytic properties of detergents are well known and, for a series of 12-carbon detergents, are consistent with a reaction involving penetration of a lipid film⁵. If the mechanism which we have proposed to account for pseudopodium induction by these compounds is correct², then the lysis of A. proteus by detergents should depend on their reactivity with negatively charged groups on the surface polysaccharide rather than on their ability to penetrate a lipid film.